FORAMINIFERAL ZONAL STANDARD FOR THE LOWER CARBONIFEROUSOF RUSSIA AND ITS CORRELATION WITH THE CONODONT ZONATION

This paper describes the zonal subdivisions of the revised Foraminiferal Scale of Russia and their correlation to conodont zones and age-equivalent beds in Western Europe and North America. The foraminiferal zonal sequence is documented in key sections and wells that cover the entire Lower Carboniferous. Boundary reference sections are proposed for most Tournaisian and Serpukhovian zones. Major evolutionary trends within the foraminifers are used to define individual zones.&nbsp

H13^{13}CN-HN13^{13}C intensity ratio as a temperature indicator of interstellar clouds

With the 30-m IRAM radio telescope, we observed several massive star forming regions at wavelengths of 3-4 and 2 mm. The temperature of the gas in the sources was estimated from the lines of CH$_{3}$CCH and from the transitions of the NH$_3$ molecule obtained during observations at the 100-m radio telescope in Effelsberg. As a result, a correlation between the integrated intensity ratios of the $J=1-0$ transitions of H$^{13}$CN and HN$^{13}$C and the kinetic temperature has been obtained. The obtained results allow us to propose the use of the intensity ratio H$^{13}$CN-HN$^{13}$C as a possible temperature indicator of interstellar clouds. We also compared the obtained estimates of the kinetic temperature with the dust temperature $T_{dust}$. As a result, no significant correlation was found.Comment: 16 pages, 7 figures, 2 tables, Accepted for publication in Astronomy Reports (2022

Deuterated molecules in regions of high-mass star formation

We present the results of our studies of deuterated molecules (DCN, DNC, DCO$^+$, N$_2$D$^+$ and NH$_2$D) in regions of high-mass star formation, which include a survey of such regions with the 20-m Onsala radio telescope and mapping of several objects in various lines with the 30-m IRAM and 100-m MPIfR radio telescopes. The deuteration degree reaches $\sim$10$^{-2}$ in these objects. We discuss its dependencies on the gas temperature and velocity dispersion, as well as spatial distributions of deuterated molecules. We show that the H$^{13}$CN/HN$^{13}$C intensity ratio may be a good indicator of the gas kinetic temperature and estimate densities of the investigated objects.Comment: 8 pages, 4 figures, to be published in Proceedings of Science (Proceedings of the conference "The Multifaceted Universe: Theory and Observations - 2022", 23-27 May 2022, SAO RAS, Nizhny Arkhyz, Russia

Fragmentation and dynamics of dense gas structures in the proximity of massive young stellar object W42-MME

We present an analysis of the dense gas structures in the immediate surroundings of the massive young stellar object (MYSO) W42-MME, using the high-resolution (0$''$.31$\times$0$''$.25) ALMA dust continuum and molecular line data. We performed a dendrogram analysis of H$^{13}$CO$^{+}$ (4-3) line data to study multi-scale structures and their spatio-kinematic properties, and analyzed the fragmentation and dynamics of dense structures down to $\sim$2000 AU scale. Our results reveal 19 dense gas structures, out of which 12 are leaves and 7 are branches in dendrogram terminology. These structures exhibit transonic-supersonic gas motions (1$<\mathcal{M}<5$) with overvirial states ($\alpha_{\rm vir}\geq2$). The non-thermal velocity dispersion-size relation ($\sigma_{\rm nt}-L$) of dendrogram structures shows a weak negative correlation, while the velocity dispersion across the sky ($\delta\mathit{V_{\rm lsr}}$) correlates positively with structure size ($L$). Velocity structure function ($S_{2}(l)^{1/2}$) analysis of H$^{13}$CO$^{+}$ data reveals strong power-law dependencies with lag ($l$) up to a scale length of $\lesssim$ 6000 AU. The mass-size ($M-R$) relation of dendrogram structures shows a positive correlation with power-law index of 1.73$\pm$0.23, and the leaf L17 hosting W42-MME meets the mass-size conditions for massive star formation. Blue asymmetry is observed in the H$^{12}$CO$^{+}$ (4-3) line profiles of most of the leaves, indicating infall. Overall, our results observationally support the hierarchical and chaotic collapse scenario in the proximity of the MYSO W42-MME.Comment: 16 pages, 13 figures, 1 Table, Accepted for publication in Monthly Notices of the Royal Astronomical Society (MNRAS) Journa

Deuterated Molecules and Temperature in Interstellar Clouds

В работе используются спектры и карты DCO+, DCN, DNC и NH2D, полученные на 30-м телескопе IRAM, для изучения процессов обогащения молекулярного газа дейтерием в пяти областях образования массивных звезд. Температура оценивалась по линиям CH3CCH и NH3, полученным при наблюдениях на 100-м радиотелескопе в Эффельсберге, а также по отношению интегральных интенсивностей переходов J = 1 − 0 H13CN и HN13C. Лучевые концентрации молекул были получены в предположении условий отличных от ЛТР. В результате мы обнаружили, что отношения D/H DCO+, DCN и DNC уменьшаются с температурой. Однако мы не обнаружили корреляций отношения D/H для NH2D.We use spectra and maps of DCO+, DCN, DNC and NH2D, obtained with the IRAM 30-m telescope, to study deuteration processes in five massive star forming regions. The temperature was estimated from the lines of CH3CCH and NH3 obtained during observations at the 100-m radio telescope in Effelsberg, as well as using the integrated intensity ratio of the J = 1−0 transitions of H13CN and HN13C. The column densities of molecules were obtained under the assumption of non-LTE conditions. As a result, we found the D/H ratios of DCO+, DCN and DNC decrease with the temperature. However, we found no correlations of the D/H ratio for NH2D.Работа выполнена при поддержке РНФ (грант 22-22-00809)

Safely probing the chemistry of Chernobyl nuclear fuel using micro-focus X-ray analysis

Detailed chemical analysis of the solidified molten fuel still residing in the stricken Chernobyl reactor unit 4 are inferred using multi-modal micro-focus X-ray analysis of a low-radioactivity proxy. A fascinating mixture of molten UO2, nuclear fuel cladding, concrete, stainless steel and other nuclear reactor components, these materials behaved like lava, solidifying to form a complex, highly radioactive glass-ceramic. Using element-specific chemical probes (micro-X-ray fluorescence and X-ray absorption spectroscopy), coupled with micro-diffraction analysis, the crystalline phase assemblage of simulants of these heterogeneous materials was established, which included “chernobylite” and a range of compositions in the (U1−xZrx)O2 solid solution. Novel insight to nuclear accident fuel chemistry was obtained by establishing the oxidation state and local coordination of uranium not only in these crystalline phases, but uniquely in the amorphous fraction of the material, which varied depending on the history of the nuclear lava as it flowed through the reactor. This study demonstrates that micro-focus X-ray analysis of very small fractions of material can yield rich chemical information, which can be applied to nuclear-melt down materials to aid decommissioning and nuclear fuel management at nuclear accident sites

High-Precision U-Pb Zircon Age Calibration of the Global Carboniferous Time Scale and Milankovitch Band Cyclicity in the Donets Basin, Eastern Ukraine

High-precision ID-TIMS U-Pb zircon ages for 12 interstratified tuffs and tonsteins are used to radiometrically calibrate the detailed lithostratigraphic, cyclostratigraphic, and biostratigraphic framework of the Carboniferous Donets Basin of eastern Europe. Chemical abrasion of zircons, use of the internationally calibrated EARTHTIME mixed U-Pb isotope dilution tracer, and improved mass spectrometry guided by detailed error analysis have resulted in an age resolution o